Violin plot in one picture

Question

I´m trying to plot a split violin but the plot of my violin is divided and I need both variables stick together to better comparison

I want something like this plot plot1

But I obtain this plot myplot

I am using this code:

library(tidyverse)
my_data <- tibble(Var_1 = c(900, 1500, 350, 1200, 750, 100,125,250,300),
                  Var_2 = c(385, 988, 150, 355,555, 900,20, 25, 500),
                  Gender = c("W", "W", "W", "M", "M", "W", "W", "M", "W"),
                  my_weights = c(2.2, 3.1, 8.2, 4.2, 5.3, 6.8, 12, 25, 1))

my_data %>%
  ggplot(aes(x = Gender , y = Var_1, weight = my_weights, fill = Gender))+
  geom_split_violin(color = "black", scale = "count")

And for the geom_split_violin () I am used this code from an old post in this page here is the post

    GeomSplitViolin <- ggproto("GeomSplitViolin", GeomViolin, 
                           draw_group = function(self, data, ..., draw_quantiles = NULL) {
                             data <- transform(data, xminv = x - violinwidth * (x - xmin), xmaxv = x + violinwidth * (xmax - x))
                             grp <- data[1, "group"]
                             newdata <- plyr::arrange(transform(data, x = if (grp %% 2 == 1) xminv else xmaxv), if (grp %% 2 == 1) y else -y)
                             newdata <- rbind(newdata[1, ], newdata, newdata[nrow(newdata), ], newdata[1, ])
                             newdata[c(1, nrow(newdata) - 1, nrow(newdata)), "x"] <- round(newdata[1, "x"])

                             if (length(draw_quantiles) > 0 & !scales::zero_range(range(data$y))) {
                               stopifnot(all(draw_quantiles >= 0), all(draw_quantiles <=
                                                                         1))
                               quantiles <- ggplot2:::create_quantile_segment_frame(data, draw_quantiles)
                               aesthetics <- data[rep(1, nrow(quantiles)), setdiff(names(data), c("x", "y")), drop = FALSE]
                               aesthetics$alpha <- rep(1, nrow(quantiles))
                               both <- cbind(quantiles, aesthetics)
                               quantile_grob <- GeomPath$draw_panel(both, ...)
                               ggplot2:::ggname("geom_split_violin", grid::grobTree(GeomPolygon$draw_panel(newdata, ...), quantile_grob))
                             }
                             else {
                               ggplot2:::ggname("geom_split_violin", GeomPolygon$draw_panel(newdata, ...))
                             }
                           })

geom_split_violin <- function(mapping = NULL, data = NULL, stat = "ydensity", position = "identity", ..., 
                              draw_quantiles = NULL, trim = TRUE, scale = "area", na.rm = FALSE, 
                              show.legend = NA, inherit.aes = TRUE) {
  layer(data = data, mapping = mapping, stat = stat, geom = GeomSplitViolin, 
        position = position, show.legend = show.legend, inherit.aes = inherit.aes, 
        params = list(trim = trim, scale = scale, draw_quantiles = draw_quantiles, na.rm = na.rm, ...))
}

Any suggestion of how make it work? Thanks

Answer 1

You are using Gender twice: in x and in fill. If you want the correct plot, you will need an other variable for the x axis. You can also cheat like this:

my_data %>%
  ggplot(aes(x = 0 , y = Var_1, weight = my_weights, fill = Gender))+
  geom_split_violin(color = "black", scale = "count")